coil test thread - coil on plug resistance measurements 30713416 9125601

Post by **abscate** » 06 Sep 2018, 14:48

Someone needed this today..

viewtopic.php?f=9&t=73023&p=385240#p385240

Post by **BlackBart** » 10 Sep 2018, 09:19

Did you say earlier you had links for part #s?

Post by **abscate** » 10 Sep 2018, 12:52

That link should be for the resistance measurements on the terminals

I added your part number to title for search, thanks!!

Post by **abscate** » 18 Nov 2019, 06:56

More info here

viewtopic.php?f=9&t=73023&p=385240#p385240

I put a known failed misfiring coil on the test bed next to a brand new one this morning and all ohm readings were identical

Sometimes, yOu have to part swap

Post by **volvolugnut** » 18 Nov 2019, 08:13

Do you have any method to heat the coil while testing? This would more closely match operating conditions for a coil. I don't know what temperature on top of the head would be, but at least coolant temperature.

volvolugnut

Post by **abscate** » 18 Nov 2019, 18:59

It gets hot under that cover. A lot of us throw that cover out

Post by **cn90** » 26 Sep 2023, 06:26

The 2005 XC90 2.5T with 132K miles, coil #4 (30713416) went bad when engine is hot, replaced with a used coil from junk yard. All is good now.

Options:

1. Do nothing and replace as I go along...

2. Replace all 5 with Bosch ($240 for 5 coils).

Question: is the coil like a light bulb, it either works or dies?
Can you have suboptimal operation of coil (not enough voltage to spark)?

Reading reviews on FCPEuro website, it looks like ppl replace all 5. What is everyone's opinion on this subject?

https://www.fcpeuro.com/products/volvo- ... 16#reviews

yanga001 · Post by **yanga001** » 26 Sep 2023, 07:01

cn90 wrote: ↑26 Sep 2023, 06:26 The 2005 XC90 2.5T with 132K miles, coil #4 (30713416) went bad when engine is hot, replaced with a used coil from junk yard. All is good now.

Options:

1. Do nothing and replace as I go along...

2. Replace all 5 with Bosch ($240 for 5 coils).

Question: is the coil like a light bulb, it either works or dies?
Can you have suboptimal operation of coil (not enough voltage to spark)?

Reading reviews on FCPEuro website, it looks like ppl replace all 5. What is everyone's opinion on this subject?

https://www.fcpeuro.com/products/volvo- ... 16#reviews

Ive helped my mechanic scrap 4-5 old 2.5t's and would say that none of them had 5 of the same coil.

He recommends just keeping a spare in the car ready to go. We do the same for my partners RDX where i keep a spare coil pack in there.

To answer your question, yea i would just keep them and replace as you go along. Unless the car will be driven by someone who cannot change a coil pack.

Post by **erikv11** » 26 Sep 2023, 09:08

I replaced all five coils back at 186k in my wife's black XC70. None were dead. Butt dyno said the car ran better after the swap but more convincing and frankly surprising data was the instant change in fuel economy, improved just under 10% based on the trip computer. That car sees very regular driving routine, I have confidence in the change.

So if those numbers hold for you then five new coils can pay off in the time it takes you to spend $2400 on gas, that's like 12,000 miles (or less). Even if you only get 5% improvement they pay off in 24,000 miles, etc. Plus you get some peace of mind for the driver for the duration (priceless!).

I kept the used coils as spares, I'll probably need them eventually.

Post by **abscate** » 29 Sep 2023, 05:26

I run new coils in two of the Volvos whose drivers either aren’t comfortable coil swapping, or highway drive, and used coils on the other three with local drivers, part swapper drivers.

I call this the Preventative maintenance PM model or Run to Fail RTF in many post, I made those names up so it sounds like I know what I’m doing